JPH0539280Y2 - - Google Patents

Description

[Detailed description of the invention] <<Industrial application field>> This invention can be applied to acetylene, ethylene, propane,
It is installed in a device that supplies flammable gas such as city gas or hydrogen, or in the supply path of piping to prevent the backfire propagation of flammable gas in the event of a flashback, as well as to cut off the supply of flammable gas. The present invention relates to a dry flashback preventer having the following characteristics.

<<Prior Art>> Conventionally, there is a flashback prevention device that prevents the backfire propagation of flammable gas and cuts off the supply of flammable gas, as disclosed in, for example, Japanese Utility Model Publication No. 7760/1983.

As shown in FIG. 4, a flashback prevention chamber 55 is formed by fitting a cutoff valve holder 54 into a flashback preventer case body 51 formed with one end open, and the cutoff valve holder 54 and case A flame extinguishing tube 56 is disposed between the inner surface of the rear end wall of the main body 51, a gas outlet 53 is formed in the peripheral wall 52 of the case body 51 corresponding to the position where the flame extinguishing tube 56 is disposed, and a gas outlet 53 is formed inside the cutoff valve holder 54. A cutoff valve chamber 57 is formed, and the outer end wall of the cutoff valve chamber 57 is formed with a gas introduction nozzle 58, a gas introduction port is formed in the gas introduction nozzle 58, and a cutoff valve body is formed on the inner end wall of the cutoff valve chamber 57. A sliding hole 60 is provided therethrough, and a shutoff valve seat 61 is formed on the peripheral wall of the opening of the shutoff valve body sliding hole 60 on the side of the shutoff valve chamber. The cutoff valve body 62 is fitted into the interior so that it can move forward and backward, and the cutoff valve spring 63 installed between it and the gas introduction nozzle 58 presses the cutoff valve body 62 toward the valve closing side. A check valve chamber 64 is formed by recessing from the fire arrester chamber 55 side, and a check valve seat 66 is formed at the tip end of the leg portion 62a, and a check valve body 67 is formed opposite to the check valve seat 66. is positioned so that the cutoff valve chamber 57 and the check valve chamber 64 can communicate with each other via a through hole 59 provided in the peripheral wall of the cutoff valve body leg 62a on the cutoff valve chamber 57 side, and the leg 62a Through hole 6 provided through the peripheral wall on the tip side
5 connects the check valve chamber 64 and the gas outlet 53 with the flame extinguishing cylinder 5.
A sliding support hole 68 is transparently provided in the rear end wall of the case body 51, and a reset rod 69 is slid into this sliding support hole 68 while facing the shutoff valve body 62. A check valve spring 70 is disposed between the reset rod 69 and the check valve body 67 to elastically bias the check valve body 67 toward the valve closing side.
9 and the sliding support hole 67, and the operation of the click stop device 71 holds the shutoff valve body 62 in the open position and the closed position. .

<<Problem to be solved by the invention>> A. In the cutoff valve chamber 57 formed inside the cutoff valve holder 54, the cutoff valve body 62 is connected to the gas introduction nozzle 5.
A sliding support hole 68 is provided in the rear end wall of the case body 51, and a reset rod 69 is connected to the shutoff valve body 62 through the sliding support hole 68. The cut-off valve body 62 is held in the open position and the closed position by the operation of a click stop device 71 which is slidably mounted so as to face each other and is interposed between the reset rod 69 and the sliding support hole 68. Because of the structure, the forward flow gas pressure acts on the clip stop device 71 to close the shutoff valve, so if the spring pressure of the clip stop device 71 is set low, the clip stop device 71 will close during the forward flow. There is a problem with it working.

(b) For this reason, the spring pressure of the click stop device 71 must be set higher than the resultant force of the forward flow gas pressure, the spring pressure of the shutoff valve spring 63, and the spring pressure of the check valve spring 70, and as a result, backfire occurs. When the flashback pressure caused by
2, there is a problem in that the valve does not close when the flashback pressure is lower than the spring pressure.

C. In addition, the check valve spring 7 is used to operate the flashback preventer.
0. Since the springs of the shutoff valve spring 63 and the click stop device 71 are all involved, the spring pressure error of each spring is added to the operating accuracy of the flashback preventer, so the accuracy of the operating set pressure is increased. Therefore, it was difficult to operate the flashback preventer accurately.

Furthermore, since the flashback prevention chamber 55 communicates with the gas outlet 53 via the flame extinguishing cylinder 56, the flashback pressure acting on the flashback prevention chamber 55 is weakened when passing through the flame extinguishing cylinder 56. Even if the flashback pressure is lower than the spring pressure of the click stop device 71 and the click stop device 71 does not operate, and the flashback pressure propagates into the flashback prevention chamber 55, the shutoff valve body 62 closes. There was a risk that it might not work.

The present invention solves the above problems and prevents the shutoff valve from closing even if the downflow gas pressure is high. It is an object of the present invention to provide a dry flashback prevention device that reliably closes a shutoff valve element even when a flashback pressure of

<Means for Solving the Problems> In order to achieve the above object, the present invention incorporates a flame extinguishing tube, a check valve body, and a shutoff valve body in a flashback prevention chamber formed in an airtight structure, and one end wall of the case body. In a dry flashback preventer in which a gas inlet is formed on one side of the circumferential wall and a gas outlet is formed on the other side, the gas outlet nozzle is inserted into the opening of the case body with one end wall open. A flashback prevention chamber is formed within the case body by fitting and fixing, a cutoff valve holder is fitted and fixed inside the flashback prevention chamber, and a flame extinguishing tube is placed between the cutoff valve holder and the inner surface of the inner wall of the back end of the case body. A gas outlet is formed in the gas outlet nozzle, a gas inlet is formed in the peripheral side wall of the case body corresponding to the flame extinguishing tube installation position, a shutoff valve chamber is formed inside the flame extinguishing tube, and a cutoff valve holder is formed. A check valve chamber is formed on the gas outlet nozzle side inside the case, and a shutoff valve body composed of a spool valve is fitted into the shutoff valve holder so that it can move forward and backward. The gas communication passage formed between the wall and the wall is configured to be closable with a shutoff valve body, and a check valve seat is formed at the end of the shutoff valve body on the check valve chamber side, and the check valve seat is installed in the check valve chamber. The check valve body is biased toward the check valve seat by the check valve spring installed between the gas outlet nozzle, and the reset rod is slid on the back end wall of the case body while facing the shutoff valve body. The reset lever is movably mounted, and the reset lever is elastically biased in a direction away from the shutoff valve body by a reset spring installed between the reset lever and the rear end wall of the case body.

《Operation》 In this invention, a shutoff valve body composed of a spool valve is fitted into a shutoff valve holder so that it can move forward and backward, and a gas communication passage formed between the shutoff valve holder and the inner wall of the case body is connected to the shutoff valve body. configured so that it can be closed with
A check valve seat is formed at the end of the cutoff valve body on the check valve chamber side, and a check valve spring installed between the check valve body attached to the check valve chamber and the gas outlet nozzle is used to prevent non-return. Since the forward flow gas pressure is biased toward the valve seat, the forward gas pressure does not actuate the shutoff valve element toward the valve closing side, but instead presses the check valve element against the check valve spring, causing it to open. let

The gas outlet nozzle is fitted and fixed into the opening of the case body, and a flame-extinguishing cylinder is placed between the gas inlet provided on the circumferential wall of the case body and the shutoff valve chamber, so that in the event of a backfire, the gas The backfire pressure propagating from the outlet acts directly on the check valve, and the resultant force with the check valve spring pressure closes the check valve body, which then moves the shutoff valve body to close the valve. Become.

At this time, the reset rod attached to the back end wall of the case body is elastically biased in the direction away from the shutoff valve body by the reset spring installed between the back end wall of the case body, and therefore due to backfire pressure. It does not take part in the closing operation of the shutoff valve element, and therefore, the reset rod has no action that causes resistance to operation.

<<Effects of the invention>> Since the present invention is constructed and operates as described above, it has the following effects.

(a) The forward gas pressure acts against the check valve spring to open the check valve body, and the backfire pressure acts to close the check valve body and the shutoff valve body due to the combined force with the spring pressure of the check valve spring. Since the check valve spring is the only spring involved in the operation of the flashback preventer during both forward flow and backfire, simply increasing the accuracy of the check valve spring will improve the accuracy of the flashback preventer. It can be operated well.

(b) Since forward flow gas pressure has no effect on operating the shutoff valve body toward the valve closing side, it can be used for gases with different pressures over a wide range from low pressure to high pressure by simply changing the spring pressure of the check valve spring. I can do it.

C. In the event of a flashback, the flashback pressure propagating from the gas outlet acts directly on the check valve without passing through the flame-extinguishing tube, so the flashback pressure acts on the flashback prevention chamber without being weakened. When a fire occurs, the check valve operates immediately and the shutoff valve body can be operated to close.

(2) Since the reset rod does not create resistance to the closing operation of the shutoff valve body due to backfire pressure, the shutoff valve body can be reliably closed even when a small amount of backfire pressure acts. be able to.

"Example" Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a longitudinal side view when the flow is in the forward direction, FIG. 2 is a longitudinal side view when the flow is backward, and FIG. 3 is a longitudinal side view when the flow is at rest.

In this flashback preventer, one end wall 6 of a case body 5 is formed in an open shape, and a gas discharge nozzle 10 is fitted inside the case body 5 to form a flashback prevention chamber 1 inside the case body 5. A shutoff valve holder 11 is fitted inside the flashback prevention chamber 1, and a flame extinguishing tube 2 made of a porous material such as sintered metal is arranged between the shutoff valve holder 11 and the inner surface of the inner wall 14 of the case body 5. The open end of the case body 5 is fixed with a nozzle holder 20 to fix the flame extinguishing tube 2, the cutoff valve holder 11, and the outlet nozzle 10 in position.

A gas outlet 9 is transparently provided in the gas outlet nozzle 10, and a gas inlet 8 is transparently provided in the peripheral side wall 7 of the case body 5 at a portion corresponding to the position where the flame extinguishing cylinder 2 is disposed.

A cutoff valve chamber 12 is formed inside the flame extinguishing tube 2 , and a part of the rear end wall 14 of the case body 5 protrudes into the cutoff valve chamber 12 in a cylindrical shape to form a gas communication passage 15 between it and the cutoff valve holder 11 . is formed. A shutoff valve body 4 constituted by a spool valve is fitted into the shutoff valve holder 11 so as to be movable back and forth, and the gas passage 15 can be closed by moving the shutoff valve body 4 back and forth.

A check valve chamber 13 is formed on the gas outlet nozzle 10 side in the cutoff valve holder 11, and a gas flow passage is formed in the center of the cutoff valve body 4 fitted inside the cutoff valve holder 11 to open the cutoff valve chamber 12. and the check valve chamber 13 are communicated with each other.

The gas flow passage within the shutoff valve body 4 is connected to the check valve chamber 13.
The side end portion is formed into a conical inner surface that widens toward the tip, and a check valve seat 16 is formed on this conical inner surface.

The check valve body 3 mounted in the check valve chamber 13 is elastically biased toward the check valve seat 16 by a check valve spring 17 installed between the check valve body 3 and the gas outlet nozzle 10.

A reset lever sliding hole 21 is transparently provided in the rear end wall 14 of the case body 5.
A reset rod 18 is slidably mounted on the valve 1 and is opposed to the shutoff valve body 4. The reset rod 18 is elastically biased in a direction away from the shutoff valve body 4 by a reset spring 19 installed between it and the case body 5, and is held down by a reset presser 22.

In the dry flashback preventer configured as described above, under normal conditions, the shutoff valve body 4 opens the gas passage 15, and the forward flow gas flowing in from the gas inlet 8 passes through the flame extinguishing tube 2 and is shut off. Flows into the valve chamber 12, passes through the gas flow passage in the cutoff valve body 4, flows into the check valve chamber 13, presses the check valve body 3 to open it,
The gas flows out from the check valve chamber 13 via the gas outlet 9.
At this time, the reset rod 18 is pressed in the direction away from the shutoff valve body 4 by the forward flow gas, and does not move the open shutoff valve body 4, so there is no effect of closing the shutoff valve body 4. do not have.

When a flashback occurs, the explosion pressure of the flashback causes flammable gas to flow from the gas outlet 9 into the check valve chamber 13.
The liquid flows directly into the check valve body 3 and, together with the elastic force of the check valve spring 17, pushes the check valve body 3 against the check valve seat 1.
6 side to close the valve, and further move the shutoff valve body 4 to the back end wall 14 side of the case body to close the valve.

As a result, the gas communication passage 15 is shut off, preventing backfire propagation and cutting off the supply of flammable gas. At this time, since the reset rod 18 is separated from the shutoff valve body 4 There is no operational resistance to the valve closing operation in step 4.

When the backfire subsides, by pushing the reset rod 18 into the case body 5, the shutoff valve body 4 can be moved to the valve opening side and the inflow of forward gas can be resumed. The reset spring 18 causes the reset rod 18 to return to the state where it is separated from the shutoff valve body 4 again.

[Brief explanation of the drawing]

Figures 1 to 3 show an embodiment of the present invention, with Figure 1 being a longitudinal side view when flowing in a forward direction, Figure 2 being a longitudinal side view when flowing backward, and Figure 3 being a longitudinal side view when at rest. FIG. 4 is a diagram corresponding to FIG. 1 showing the prior art. DESCRIPTION OF SYMBOLS 1... Flashback prevention chamber, 2... Flame extinguishing tube, 2... Check valve body, 4... Shutoff valve body, 5... Case body, 6...
... One end wall of 5, 7... Circumferential side wall of 5, 8... Gas inlet, 9... Gas outlet, 10... Gas outlet nozzle, 11... Shutoff valve holder, 12... Shutoff valve chamber, 13 ...Check valve chamber, 14...Back end wall of 5, 1
5...Gas communication passage, 16...Check valve seat, 17...
Check valve spring, 18... Reset rod, 19... Reset spring.

Claims (1)

[Scope of Claim for Utility Model Registration] A flame-extinguishing tube 2, a check valve body 3, and a shutoff valve body 4 are incorporated into a flashback prevention chamber 1 formed in an airtight structure, and one end wall 6 and a circumferential side wall 7 of a case body 5 are installed. In a dry flashback preventer in which a gas inlet 8 is formed on one side and a gas outlet 9 is formed on the other side, a gas outlet nozzle 10 is inserted into an opening of a case body 5 in which one end wall 6 is formed in an open shape. A flashback prevention chamber 1 is formed in the case body 5 by fitting and fixing, and a shutoff valve holder 11 is fitted and fixed in the flashback prevention chamber 1, and the shutoff valve holder 11 and the inner surface of the rear end wall 14 of the case body 5 are fitted and fixed. A flame extinguishing tube 2 is arranged between the gas outlet nozzle 10, a gas outlet 9 is formed in the gas outlet nozzle 10, and a gas inlet 8 is formed in the peripheral side wall 7 of the case body 5 corresponding to the position where the flame extinguishing tube 2 is disposed. A cutoff valve chamber 12 is formed inside the flame-extinguishing cylinder 2, a check valve chamber 13 is formed inside the cutoff valve holder 11 on the side of the gas outlet nozzle 10, and a cutoff valve body 4 composed of a spool valve is provided in the cutoff valve holder 11. is fitted into the interior so as to be movable forward and backward, and the gas communication passage 15 formed between the shutoff valve holder 11 in the shutoff valve chamber 12 and the rear end wall 14 of the case body 5 is configured to be closable with the shutoff valve body 4, A check valve seat 16 is formed at the end of the cutoff valve body 4 on the check valve chamber 13 side, and the check valve body 3 is installed in the check valve chamber 13 and is installed between the gas outlet nozzle 10. A stop valve spring 17 is used to pressurize the check valve seat 16, and a reset rod 18 is slidably mounted on the back end wall 14 of the case body 5 in a state facing the shutoff valve body 4.
Connect this reset rod 18 to the back end wall 14 of the case body 5.
A reset spring 19 installed between the shutoff valve body 4
A dry flashback preventer characterized by being biased in a direction away from the air.